Magnetic tape drive

ABSTRACT

A magnetic tape drive is equipped with a travel device for running a magnetic tape and a plurality of guides for guiding the magnetic tape, which is running, along a predetermined route. Each of the guides has a roller portion and a flange portion. A surface hardening treatment is dispensed to a guide out of the guides where a ratio of a peripheral speed of the guide for a running speed of the magnetic tape is not more than 0.9.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic tape drive forrecording/reproducing magnetic information for a magnetic tape.

2. Description of the Related Art

A magnetic tape drive is equipped with a travel device for running amagnetic tape and a plurality of guides for guiding the magnetic tape,which runs, along a predetermined route (for example, see paraphrase0058 and FIG. 1 in Japanese Patent Laid-Open Publication 2002-530791).In this magnetic tape drive a running magnetic tape is designed to behung across a plurality of guides arranged at predetermined positions.And each of these guides is configured, as well known, of a rollerportion of a cylindrical shape freely rotationally supported by a shaftaround a center axis and a flange portion arranged on up/down ends ofeach roller.

In such the magnetic tape drive, it is designed so that magneticinformation is sent to a magnetic head while a magnetic tape, which isreceived on a periphery of the roller portion, is regulated in a lateraldirectional movement thereof by the flange portion; thereby the magneticinformation is recorded on the magnetic tape; and the recorded magneticinformation is reproduced.

In the meantime, because if such the magnetic tape drive is used for aninspection of magnetic characteristics of the magnetic tape and alibrary equipping many magnetic cartridges where magnetic informationdata is stored, the magnetic tape loaded on the magnetic tape drive isin no use or nearly in no use, the guides are remarkably abraded away bya large grinding force of the magnetic tape. In short, for example, asshown in FIG. 9, a groove G is dug into a flange portion 20 a of a guide20 where an edge of a magnetic tape MT abrades as use times of amagnetic tape drive are repeated. This tendency noticeably appears in amagnetic tape drive where a running speed of a magnetic tape isheightened and magnetic information is recorded/reproduced at a highspeed. And such the groove G being dug, the magnetic tape MT guided bythe guide 20 is oscillated in lateral directions (in up/down directionsin FIG. 9) by the groove G in order of a micro meter (μm).

On the other hand, nowadays a track width tends to be narrowed in orderto achieve a high density recording of a magnetic tape. As a result,when a magnetic tape drive is used, the above oscillation of themagnetic tape becomes a cause of a tracking error even if an oscillationwidth thereof is in order of the micro meter.

Consequently, is strongly requested a magnetic tape drive, which doesnot generate the tracking error, not depending on recording density of amagnetic tape even if used over a long period.

SUMMARY OF THE INVENTION

The inventor has found that when in each of a plurality of guidesarranged at a magnetic tape drive a ratio of a peripheral speed of eachguide for a running speed of a magnetic tape becomes lower than apredetermined value, a flange portion of the guide is peculiarly groundby the magnetic tape, and thereby has reached the present invention.

A first aspect of the present invention to solve the problem is amagnetic tape drive comprising a travel device for running a magnetictape and a plurality of guides guiding the magnetic tape, which isrunning, along a predetermined route, and a surface hardening treatmentis dispensed to a relevant guide out of the guides, whose ratio of aperipheral speed for a running speed of the magnetic tape is not morethan 0.9.

In the magnetic tape drive, when the travel device runs the magnetictape while the guides guide it along the predetermined route, themagnetic tape is regulated by flange portions of the guides in amovement of lateral directions thereof. In accordance with such themagnetic tape drive, because when the running magnetic tape is guided bythe guides, the surface hardening treatment is dispensed to the relevantguide out of the guides, whose ratio of the peripheral speed for therunning speed of the magnetic tape is not more than 0.9, that is, theguide where a difference between the running speed of the magnetic tapeand a rotation speed of the guide is not less than the predeterminedvalue, the flange portion of the relevant guide becomes difficult to beground by edges of the magnetic tape. Accordingly, even when themagnetic tape drive is used over a long period, the magnetic tape is notoscillated in the lateral directions thereof.

On the other hand, in accordance with knowledge of the inventor a guide,where a wrap angle of the magnetic tape is not more than 90 degrees, isremarkably bad in a rotation following ability. Meanwhile, the wrapangle described here means a range of a plane angle where the magnetictape hung across a periphery of a guide contacts the periphery, that is,a contact angle (see FIG. 2B).

Accordingly, in such the magnetic tape drive the surface hardeningtreatment is preferable to be dispensed to the relevant guide out of theguides, whose ratio of the peripheral speed for the running speed of themagnetic tape is not more than 0.9 and whose wrap angle of the magnetictape is not more than 90 degrees.

Even when the magnetic tape drive is used over a long period, it moresurely suppresses an oscillation of a magnetic tape in lateraldirections thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a magnetic tape drive related to anembodiment of the present invention.

FIG. 2A is a perspective view showing a state around a guide used in themagnetic tape drive of FIG. 1; FIG. 2B is a pattern drawing showing astate where a magnetic tape contacts a guide used in the magnetic tapedrive of FIG. 1.

FIG. 3 is a partial section drawing of a guide used in the magnetic tapedrive of FIG. 1.

FIG. 4 is a schematic drawing showing arrangement positions in amagnetic tape drive used for an abrasion resistance test of a guide.

FIG. 5 is a pattern drawing of a guide sample provided for anobservation through a laser microscope.

FIG. 6 is a microscope photo of a guide sample (example of the presentinvention).

FIG. 7 is a microscope photo of a guide sample (comparison example).

Each of FIGS. 8A and 8B is a partial section drawing of a guide used ina magnetic tape drive related to other embodiments.

FIG. 9 is a conceptual drawing showing a guide used in a conventionalmagnetic tape drive.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENTS

Here will be described one embodiment of the present invention relatedto a magnetic tape drive (hereinafter simply referred to as a “drive”)in detail, referring to the drawings as needed. In referred drawingsFIG. 1 is a schematic drawing of a magnetic tape drive related to anembodiment of the present invention; FIG. 2A is a perspective viewshowing a state around a guide used in the magnetic tape drive of FIG.1; FIG. 2B is a pattern drawing showing a state where a magnetic tapecontacts a guide used in the magnetic tape drive of FIG. 1; and FIG. 3is a partial section drawing of a guide used in the magnetic tape driveof FIG. 1 when the guide is cut at a plane along a rotation axisthereof.

The drive exemplified in the embodiment is one according to the LTOstandard (Linear Tape-Open) and is designed to record/reproduce magneticinformation at a high speed even when a magnetic tape of a magnetic tapecartridge runs in any forward/reverse of bi-directions.

As shown in FIG. 1, a drive A related to the embodiment comprises afirst gear 11 a and a second gear 11 b; a reel 12; a magnetic head 14; afirst guide 15 a and a second guide 15 b (simply referred to as “guide15” when not specifying a guide); drive motors not shown for driving thefirst gear 11 a and the second gear 11 b, respectively; and a casing 16for housing the members 11 a, 11 b, 12, 14, 15 a, and 15 b.

The first gear 11 a rotates a reel 17 of a magnetic tape cartridge MCloaded in the drive A and is designed to rotate in any forward/reverseof bi-directions by a drive motor not shown.

The reel 12 (hereinafter referred to as a “drive-side reel 12”) winds amagnetic tape MT, which is sent out from the reel 17 (hereinafterreferred to as a “cartridge-side reel 17”) of the magnetic tapecartridge MC, and sends out the magnetic tape MT, which is wound, to thecartridge-side reel 17.

The second gear 11 b rotates the drive-side reel 12 in a directionopposite to a rotation direction of the cartridge-side reel 17 and isdesigned to rotate in any forward/reverse of bi-directions of a by adrive motor not shown.

The magnetic head 14 records magnetic information on the magnetic tapeMT, which reciprocates between the cartridge-side reel 17 and thedrive-side reel 12, and also reproduces the recorded magneticinformation. In the magnetic head 14 is used a compound head, whichcomprises a read element such as a magnetoresistive effect element and awrite element such as an electromagnetic induction element. The magnetichead 14 is arranged so as to be able to contact the magnetic tape MT,which runs with being guided to a predetermined route by the guide 15described next.

The first guide 15 a and the second guide 15 b guide the magnetic tapeMT, which is sent out from the magnetic tape cartridge MC(cartridge-side reel 17), so as to head for the drive-side reel 12 viathe magnetic head 14; and otherwise guide the magnetic tape MT, which iswound on the drive-side reel 12, so as to head for the cartridge-sidereel 17 via the magnetic head 14. By these first guide 15 a and secondguide 15 b is determined a running route of the magnetic tape MT in thedrive A.

As obvious jointly in reference to FIG. 2A, such the guide 15 isdesigned to be supported by a rotation shaft 15 c, which extends to avertical direction of the casing 16, and to be able to rotate around therotation shaft 15 c. And the guide 15 is designed so that a flangeportion 15 e thereof regulates a movement of lateral directions of therunning magnetic tape MT while the guide 15 itself rotates by therunning magnetic tape MT being hung across a periphery of a rollerportion 15 d thereof.

In addition, as shown in FIG. 2B, the running magnetic tape MT, which ishung across such the guide 15, contacts a periphery thereof in a rangeof opening at a predetermined angle θ from a center C of the rotationshaft 15 c. Hereinafter the contact angle is referred to as a wrapangle.

The wrap angle θ in the first guide 15 a gradually becomes small as themagnetic tape MT is sent out from the cartridge-side reel 17 to thedrive-side reel 12; the wrap angle θ in the second guide 15 b graduallybecomes small as this sent-out magnetic tape MT is wound on thedrive-side reel 12. On the contrary, the wrap angle θ in the secondguide 15 b gradually becomes large as the magnetic tape MT is sent outfrom the drive-side reel 12 to the cartridge-side reel 17; the wrapangle θ in the first guide 15 a gradually becomes large as this sent-outmagnetic tape MT is wound on the cartridge-side reel 17. In the drive Arelated to the embodiment the guide 15 is arranged at positions wherethe wrap angle θ, which thus fluctuates when the magnetic tape MTreciprocates between the cartridge-side reel 17 and the drive-side reel12, always becomes not more than 90 degrees. In the drive A related tothe embodiment the wrap angle θ is set in such the range, and therebythe drive A is designed so that a frictional resistance of the magnetictape MT for the first guide 15 a and the second guide 15 b is reduced, ahigh speed running of the magnetic tape MT can be made, and magneticinformation for the magnetic tape MT is quickly recorded/reproduced. Andin the guide 15 thus arranged a ratio of a peripheral speed of theroller portion 15 d for a running speed of the magnetic tape M(hereinafter simply referred to as a “rotation following ratio of theguide 15”) is designed to be not more than 0.9 when the magnetic tape MTis run by a travel device.

As shown in FIG. 3, in such the guide 15 a hardening treatment isdispensed to a surface of a base metal B and a hardened layer H isformed on the surface. Meanwhile, although in FIG. 3 the base metal Band the hardened layer H are clearly discriminatingly depicted, aninterface thereof is not always clear, depending on a material of thehardened layer H.

In the hardened layer H a hardening treatment such as a soft-nitrizingtreatment, carburizing and quenching, and induction hardening isdispensed to the base metal B or a hard film is formed on the surface ofthe base metal B, for example, by a known thin-film-forming method suchas a sputtering method.

The material of the hardened layer H is not specifically limited, andfor example, are cited titan nitride (TiN), chromium nitride (CrN),titan aluminum nitride (TiAlN), tungsten carbide-cobalt (WC-Co),diamond-like carbon (DLC), and the like. Meanwhile, in the hardenedlayer H, which is formed on the base metal B, a polish treatment mayalso be dispensed so that a surface thereof becomes a predeterminedsmoothness.

Next, will be described operation of the drive A related to theembodiment, referring to FIGS. 1, 2A, 2B, and 3 as needed.

First, the magnetic tape cartridge MC is loaded in the drive A and thefirst gear 11 a and the second gear 11 b are rotated by drive motors notshown, and thereby the magnetic tape MT wound on the cartridge-side reel17 is sent out to the drive-side reel 12; This sent-out magnetic tape MTis wound to the drive-side reel 12 and thereby runs between thecartridge-side reel 17 and the drive-side reel 12.

Then the first guide 15 a and the second guide 15 b guide the runningmagnetic tape MT so as to contact the magnetic head 14. Because at thistime each wrap angle θ of the first guide 15 a and the second guide 15 bis set to become a range of not more than 90 degrees, a frictionalresistance of the magnetic tape MT for the guide 15 is reduced. As aresult, because the magnetic tape MT can be stably run at a high speed,magnetic information can be recorded/reproduced at a high speed for themagnetic tape MT. On the contrary, because in the first guide 15 a andthe second guide 15 b the wrap angle θ is set in a range of not morethan 90 degrees and a contact area of the guide 15 and the magnetic tapeMT is reduced, the rotation following ratio of the guide 15 becomes notmore than 0.9. That is, a difference occurs between a running speed ofthe magnetic tape MT and a peripheral speed of the guide 15.

On the other hand, because the surface hardening treatment is dispensedto the first guide 15 a and the second guide 15 b, the flange portion 15e thereof becomes difficult to be ground. In other words, even when thedrive A is used over a long period, the magnetic tape MT is notoscillated in the lateral directions thereof. Accordingly, the drive Adoes not generate a tracking error, not depending on recoding density ofthe magnetic tape MT loaded therein being high or low, and can be usedfor an inspection of the magnetic tape MT and a library over a longperiod.

Next, because an abrasion resistance test of a guide used in a drive ofthe present invention was performed, a test result thereof will bediscussed.

The drive used in the abrasion resistance test is, as shown in FIG. 4,designed so that the magnetic tape MT, which runs between a pair ofreels R1 and R2, is guided along a predetermined route by guidesarranged at positions #1, #2, #3, and #4. And out of these guides, onperipheries of guides arranged at the positions #2 and #3 a groove notshown is formed and adjusts a running speed of the magnetic tape MT andperipheral speeds of rotating guides so as to become nearly equal, thatis, each the rotation following ratio of the guides approximates 1. Inaddition, as a guide arranged at the position #1, is used a stainlesssteel guide, where a hardened layer of titan nitride (TiN) is formed ona surface thereof.

In the abrasion resistance test, firstly setting a tension 1N andrunning the magnetic tape MT at 6 meters per second, measure a rotationspeed of each guide. And here make a direction of sending the magnetictape MT from the reel R1 to the reel R2 a forward direction and areverse thereof a reverse direction, measure the rotation speed of eachguide when running the magnetic tape MT in the forward and reversedirections. The result is shown in Table 1. Meanwhile, a rotation speed,which is described in a column of “Start-Side Speed” in Table 1, is thatof each guide when starting to send the magnetic tape MT from the reelR1, that is, when the magnetic tape MT is at a position X in FIG. 4. Onthe other hand, a rotation speed, which is described in a column of“Finish-Side Speed” in Table 1, is that of each guide when finishing tosend the magnetic tape MT from the reel R1, that is, when the magnetictape MT is at a position Y in FIG. 4. TABLE 1 Rotation Speed of Guide(rotation per second): The Present Invention Forward Direction ReverseDirection Start-Side Finish-Side Start-Side Finish-Side Guide No. SpeedSpeed Speed Speed #1 78 16 21 17 #2 164 164 164 164 #3 165 164 165 164#4 48 40 87 164

As obvious from Table 1, it turns out that the guide arranged at theposition #1 is far lower than 0.9 in the rotation following ratiothereof.

Next, run a commercial new magnetic tape in such the drive in theforward and reverse directions, respectively. And observe an abrasionstate of a guide arranged at the position #1 by a laser microscope afterrunning the magnetic tape MT by 12,000 meters. Meanwhile, as shown inFIG. 5, a sample provided for this observation (hereinafter referred toas a “guide sample”) is something that is cut out from the guide 15 withleaving the flange portion 15 e.

FIG. 6 is a microscope photo of a #1 guide sample when running themagnetic tape MT.

As obvious from FIG. 6, it turns out that in the guide 15, which is usedfor a magnetic tape drive of the present invention, the flange portion15 e is not abraded away even when the guide 15 is arranged at aposition where the rotation following ratio is far lower than 0.9.

Next, as a comparison example, measure a rotation speed of each guidefor a conventional stainless steel guide same as described above whenrunning the magnetic tape MT. The result is shown in Table 2. TABLE 2Rotation Speed of Guide (rotation per second): Comparison ExampleForward Direction Reverse Direction Start-Side Finish-Side Start-SideFinish-Side Guide No. Speed Speed Speed Speed #1 74 20 20 17 #2 165 165165 165 #3 164 164 164 164 #4 66 57 93 163

As obvious from Table 2, it turns out that the guide arranged at theposition #1 is far lower than 0.9 in the rotation following ratiothereof.

In addition, for the conventional stainless steel guide same asdescribed above, observe an abrasion state of a guide arranged at theposition #1 by a laser microscope. FIG. 7 is a microscope photo of a #1guide sample when running the magnetic tape MT.

As obvious from FIG. 7, in a flange portion used for a conventionalmagnetic tape drive, it turns out that a portion receiving the magnetictape MT, which is running, is remarkably abraded away.

As obvious from the abrasion resistance tests thus described, because ifa guide used for the drive of the present invention is arranged at aposition where the rotation following ratio is lower than 0.9, theflange portion 15 e (see FIG. 2A) is not abraded away, the magnetic tapeMT guided by the guide 15 is not oscillated in the lateral directionsthereof.

Thus, although the drive of the present invention is concretelydescribed, based on the embodiment, the invention is not at all limitedto such the embodiment and various variations are available withoutdeparting from the spirit and scope of the invention.

For example, although as the first guide 15 a and the second guide 15 bare applied ones where a hardening treatment is dispensed to allsurfaces thereof, the present invention is not limited thereto; forexample, as shown in FIG. 8A, are available the first guide 15 a and thesecond guide 15 b, where the hardened layer H is formed on nothing butan inner surface I of the flange portion 15 e arising from a peripherythereof.

In addition, as shown in FIG. 8B, in the first guide 15 a and the secondguide 15 b the roller portion 15 d and the flange portion 15 e isconfigured of different members and the flange portion 15 e, where asurface hardening treatment is dispensed, may be joined to the rollerportion 15 d.

Furthermore, although in the embodiment the drive according to the LTOstandard, that is, a single-reel cartridge drive is exemplified, thepresent invention is not limited thereto and a two-reel cartridge driveis also available.

Still furthermore, a guide used for the magnetic tape drive of thepresent invention is applicable to one arranged within a magnetic tapecartridge.

1. A magnetic tape drive comprising: a travel device for running amagnetic tape; and a plurality of guides for guiding said magnetic tape,which is running, along a predetermined route, wherein each of saidguides comprises a roller portion and a flange portion, wherein asurface hardening treatment is dispensed to a guide out of said guides,and wherein a ratio of a peripheral speed of the guide for a runningspeed of said magnetic tape is not more than 0.9.
 2. A magnetic tapedrive according to claim 1, wherein a wrap angle of said magnetic tapeis not more than 90 degrees in a guide, and wherein said ratio of aperipheral speed of the guide is not more than 0.9.
 3. A magnetic tapedrive according to claim 1, wherein a surface hardening treatment isdispensed to all surface of each of said guides.
 4. A magnetic tapedrive according to claim 2, wherein a surface hardening treatment isdispensed to all surface of each of said guides.
 5. A magnetic tapedrive according to claim 1, wherein a surface hardening treatment isdispensed to nothing but an inner surface of a flange portion arisingfrom a periphery of a roller portion of each of said guides.
 6. Amagnetic tape drive according to claim 2, wherein a surface hardeningtreatment is dispensed to nothing but an inner surface of a flangeportion arising from a periphery of a roller portion of each of saidguides.
 7. A magnetic tape drive according to claim 1, wherein a rollerportion and flange portion of each of said guides is configured ofdifferent members and said flange portion is joined to said rollerportion, and wherein a surface hardening treatment is dispensed to theflange portion.
 8. A magnetic tape drive according to claim 2, wherein aroller portion and flange portion of each of said guides is configuredof different members and said flange portion is joined to said rollerportion, and wherein a surface hardening treatment is dispensed to theflange portion.
 9. A magnetic tape drive according to claim 1, wherein amaterial of a hardened layer formed on said guides by said surfacehardening treatment is any of titan nitride, chromium nitride, titanaluminum nitride, tungsten carbide-cobalt, and diamond-like carbon. 10.A magnetic tape drive according to claim 2, wherein a material of ahardened layer formed on said guides by said surface hardening treatmentis any of titan nitride, chromium nitride, titan aluminum nitride,tungsten carbide-cobalt, and diamond-like carbon.
 11. A magnetic tapedrive according to claim 3, wherein a material of a hardened layerformed on said guides by said surface hardening treatment is any oftitan nitride, chromium nitride, titan aluminum nitride, tungstencarbide-cobalt, and diamond-like carbon.
 12. A magnetic tape driveaccording to claim 4, wherein a material of a hardened layer formed onsaid guides by said surface hardening treatment is any of titan nitride,chromium nitride, titan aluminum nitride, tungsten carbide-cobalt, anddiamond-like carbon.
 13. A magnetic tape drive according to claim 5,wherein a material of a hardened layer formed on said guides by saidsurface hardening treatment is any of titan nitride, chromium nitride,titan aluminum nitride, tungsten carbide-cobalt, and diamond-likecarbon.
 14. A magnetic tape drive according to claim 6, wherein amaterial of a hardened layer formed on said guides by said surfacehardening treatment is any of titan nitride, chromium nitride, titanaluminum nitride, tungsten carbide-cobalt, and diamond-like carbon. 15.A magnetic tape drive according to claim 7, wherein a material of ahardened layer formed on said guides by said surface hardening treatmentis any of titan nitride, chromium nitride, titan aluminum nitride,tungsten carbide-cobalt, and diamond-like carbon.
 16. A magnetic tapedrive according to claim 8, wherein a material of a hardened layerformed on said guides by said surface hardening treatment is any oftitan nitride, chromium nitride, titan aluminum nitride, tungstencarbide-cobalt, and diamond-like carbon.